1. Field of the Invention
An aspect of the present invention relates to a digital broadcasting transmission/reception system, and more specifically, to a digital broadcasting transmission system generating stuff byte in a Moving Picture Experts Group-2 transport stream (MPEG-2 TS), and operating and transmitting a pattern of known data using the stuff byte to improve reception performance and equalization performance of a reception system and a signal processing method thereof.
2. Description of the Related Art
The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB) method, a U.S.-oriented terrestrial waves digital broadcasting system, is a single carrier method that uses a field sync by 312 segment unit. Accordingly, reception performance is not good in poor channels, especially in a Doppler fading channel.
FIG. 1 is a block diagram of a transmitter/receiver of a general U.S.-oriented terrestrial waves digital broadcasting system according to the ATSC digital television (DTV) standards.
The digital broadcasting transmitter of FIG. 1 has a data randomizer (110) for randomizing an MPEG-2 TS, an Reed-Solomon (RS) encoder (120) of a concatenated coder form for correcting errors generated by channels, an interleaver (130), and a ⅔ rate trellis encoder (140). The encoded data is mapped in 8 level symbols and field syncs and segment syncs are inserted into the data as shown in FIG. 2. After that the field syncs and the segments syncs are inserted, pilots are inserted into the data, the data is then VSB-modulated, upconverted into RF and transmitted.
Meanwhile, the digital broadcasting receiver of FIG. 1 lowers the RF signal to baseband, demodulates and equalizes the lowered signal, performs channel decoding, and restores the original signal in a reverse order of the digital broadcasting transmitter.
FIG. 2 shows a vestigial sideband (VSB) data frame of the U.S.-oriented DTV system. In FIG. 2, one frame consists of two fields and each field includes 312 data segments and a field sync segment. Each segment also has segment syncs of four symbols and data symbols of 828 symbols.
As shown in FIG. 1, the digital broadcasting transmitter randomizes the MPEG-2 TS through the randomizer (110). The randomized data is outer-coded through the RS encoder (120) which is an outer coder, and the outer-coded data is dispersed through the interleaver (130). The interleaved data is inner-coded by 12 symbol unit through the trellis encoder (140), and the inner-coded data is mapped in an 8 level symbol and the field syncs and segment syncs are inserted as shown in FIG. 2. Thereafter, the data includes DC offset to generate the pilot, and the data is VSB-modulated, upconverted to an RF signal and transmitted.
Meanwhile, the digital broadcasting receiver of FIG. 1 converts an RF signal received through a channel into a baseband signal through a tuner/IF (not shown). The baseband signal is synchronization-detected and demodulated through a demodulator (210), and any distortion by multi-path channel is compensated through an equalizer (220). The equalized signal is error-corrected and decoded into symbol data through a Viterbi decoder (230). The decoded data, which has been dispersed by the interleaver (130) of the transmitter, is rearranged through a de-interleaver (240), and the deinterleaved data is error-corrected through an RS decoder (250). The error-corrected data is de-randomized through a derandomizer (260) and output into an MPEG-2 TS.
In the VSB data frame of the US-oriented terrestrial waves DTV system of FIG. 2, one segment corresponds to one MPEG-2 packet. In FIG. 2, the segment sync and field sync, which are sync signals, are used for synchronization and equalization. The field sync and segment sync are known sequences and used as training data in the equalizer.
The VSB method of the U.S.-oriented terrestrial waves digital television system of FIG. 1 is a single carrier system and has the capacity to remove multipath in a multipath fading channel with Doppler. However, if the known sequence such as a field sync is used a lot, it is easier to estimate the channel and compensate the signal distorted by a multi-path in the equalizer using the known sequence.
However, as shown in the VSB data frame of the U.S.-oriented terrestrial waves digital television system of FIG. 2, a field sync which is a known sequence appears in every 313th segment. This is not frequent so the capacity to remove the multipath and equalize the received signal using this known sequence, is low.